1. Field of the Invention
The present invention relates to navigation and steering schemes for use in marine, land, and air directional control. More particularly, the present invention relates to the display and expression of position and navigation information in a simple and direct format for immediate identification of the user's present location relative to a desired location.
2. Description of Related Art
Advances in data storage and display technologies have made electronic charts a necessary means to efficiently and accurately assist users in determining their positions relative to a desired destination. For example, when electronic charts are integrated with a positioning system such as the global positioning system (GPS), the user's position can be displayed in real time on a chart depicting the user's area. Such information is particularly useful for operators of marine, land, and air vehicles who continuously need to know of their positions around the earth. However, simply knowing one's position on a chart is generally not sufficient. It is also particularly helpful to know whether the present course of direction is correct. That is, users typically need to know if their present course will take them where they want to go. The desired destination could be the next waypoint on the route or some other location on the chart.
Current commercially available electronic chart display implementations typically indicate relevant geographic features, routes and waypoints, the user's position, and the user's track. However, such displays do not include integrated steering information informing the user whether (1) the user's current course is properly directing the user towed the desired destination, and (2) any course corrections are needed to ensure the user arrives at this destination. Rather, in conventional chart display schemes, a separate display medium must be implemented. However, to review the additional course information, the user must switch between a position display and a steering correction display for a complete understanding of the total navigation situation.
For example, FIG. 1(a) shows the current implementation in most commercial systems. A desired route with dotted waypoints 102 is indicated by the straight lines 104 which comprise the intended track 114. The destination waypoint is shown as a circled dot 110, and the dotted line 112 indicates the user's actual track. In the example, the arrow 116 at the top end of the dotted line 112 shows the user's position and current heading. However, to retrieve steering data and correction information, the user must refer to FIG. 1(b). FIG. 1(b) represents a steering screen which is used to correct a current route and, thus, to enable users to steer themselves toward a desired destination waypoint. That is, the object of the steering screen is to point the illustrated arrow 118 toward the flag 120. When the arrow 118 points at the flag 120, the course-over-ground indication (COG) will match the bearing indication (BRG).
However, to reach the point where the user is traveling toward the destination waypoint, numerous attempts at directing and redirecting the arrow toward the flag may be required. Consequently, however, the user must switch back and forth from screen-to-screen to determine if the track is correct according to the graphical as well as numerical representation. Because there are no visual or graphical cues to indicate whether the user is successfully steering toward the desired path, immediate course correction is difficult.